1. Field of Invention
This invention pertains to the production of coke from coal. More particularly, this invention pertains to an improved method and apparatus for transporting and quenching hot coke while collecting dust during transportation of the hot coke from a coke production oven through a quenching apparatus.
2. Description of the Related Art
Coke is a solid carbon fuel and carbon source which is typically manufactured from coal and is used in numerous applications, for example, to melt and reduce iron ore in the production of steel. Coke ovens have been used for many years to convert coal into coke in a process known generally as “coking.” During the coking process, finely crushed coal is heated under controlled temperature conditions to devolatilize the coal and form a fused mass of coke known as a “cake” having a predetermined porosity and strength. In one known process, coke used for refining metal ores is produced by batch feeding pulverized coal into an oven which is sealed and heated to high temperatures under closely controlled atmospheric conditions. Once a batch of coal is heated into caked coke, the coke is pushed from the coke oven and transported to a quenching apparatus, where the coke is quenched with water. Thereafter, the quenched coke may be screened and loaded onto suitable transportation devices for shipment to an end user. Because the production of coke is a batch process, multiple coke ovens are typically operated simultaneously in a configuration known as a “coke oven battery.”
One of the problems associated with the coke making process is maintaining safety and coordination of the various machines and equipment used in the coke production process. In certain prior art methods for producing coke, the process for transporting hot caked coke from a coke oven to a quenching apparatus to be quenched utilizes four independent heavy machines for assisting an operator in accessing and effecting transportation of the hot caked coke. Specifically, a heavy lifting machine is provided to remove a door on a coke oven to expose an output portal of the coke oven. A separate vehicular machine, referred to as a “hot car,” is provided to align with the coke oven output portal, whereupon a ram internal to the coke oven pushes hot caked coke from within the oven onto the hot car. The hot car then transports the received hot caked coke to a stationary ram which pushes the coke from the hot car onto another vehicular machine, called a “quench car.” The quench car is adapted to carry the hot coke to a quenching apparatus to be quenched, and thereafter, to dump the quenched coke onto a wharf for further transportation. These machines, when used at the same time, can interfere with one another. For example, the hot car, the stationary ram, and the quench car must each be aligned with one another prior to the stationary ram pushing the hot coke from the hot car onto the quench car. In addition, the door machine can occupy the same space as the hot car, although not normally at the same time. Uncoordinated and/or misaligned use of these machines can result in collision or other such accidents, potentially resulting in spillage of the hot coke batch, injury, and/or equipment damage.
Another problem associated with some heat recovery coke making processes is dusting and pollution associated with transportation of the coke as it is discharged from the coke ovens. In one known process, a hot car is provided for transporting hot coke from a coke oven to a quenching apparatus. In this process, the hot car is positioned tangential to and at an elevation lower than an output portal of the coke oven. Once a charge of coal is converted into hot caked coke within the coke oven, the hot caked coke is pushed from the coke oven through the output portal and allowed to drop onto the hot car, thus allowing the caked coke to separate into smaller pieces of loose bulk coke. As the caked coke drops into the hot car, a significant amount of coke dust and other pollution is generated at the location of the coke oven output portal. In use of a coke oven battery employing numerous coke ovens, this process of discharging hot caked coke from a coke oven into a hot car, and subsequent significant dust and pollution generation, is repeated at the location of each coke oven output portal in the coke oven battery. Thus, not only does the above-described process produce a significant amount of dust and other pollution, but such dust and other pollution is produced and discharged over a large area encompassing each of the coke oven output portals in the coke oven battery. This dust is generally captured with low efficiency by a large shed which covers the entire coke side of the battery including the hot car and related tracks. Dust which is partially captured within the shed may be evacuated through a fabric filter for additional particulate removal. This de-dusting practice is costly, inefficient, and a difficult environment from which to operate with personnel and equipment.
In certain coke oven batteries employing numerous ovens, the coke discharged from the oven falls into a car at each oven and also generates a plume of dust and other pollutants. The typical control device in this case is a traveling hood which can move over the entire battery and be positioned at the oven being pushed. The hood discharges into a duct which is used in conjunction with a fabric filter for dust removal. This technique, although effective, is costly and difficult to maintain.
In another process, a hot car having a planar receiving surface is positioned tangential to and at an elevation equal to the base of the output portal of the coke oven. In this process, hot coke is pushed from the coke oven through the output portal onto the planar receiving surface of the hot car in a unitary slab. The unitary slab of hot coke is transported to a quenching apparatus, where it is quenched prior to separation of the quenched coke into usable pieces. While this process results in less generation of dust near the coke oven output portals than the above-described process, quenching the coke in a unitary slab form rather than loose bulk form results in non-uniform quenching of the coke comprising the unitary slab. Furthermore, coke quenched in a denser, unitary slab form is more difficult to quench uniformly than coke which is quenched in loose bulk form.
Another transportation and quenching method used previously in non recovery and heat recovery coke making applications utilizes only one car which removes the oven door and aligns the coke car for receiving a unitary slab. The hot coke is transferred to the car, transported along a set of tracks to a quenching apparatus, and quenched as a unitary slab in the car. However, the occupation of the single car by a single coke batch through the entire process of unloading the coke oven, transporting, and quenching the coke results in increased cycle time between oven discharges. Furthermore, this type of car is typically uncovered and permits an undesirable amount of fugitive emissions during transport. This type of combination hot car and quench car must typically also travel along its tracks to the quench tower and wharf where coke is quenched and side-dumped from the car onto a wharf. In doing so, the car must stop precisely at an end location along its tracks to avoid over running the tracks which terminate at the wharf. Such precise car movements are therefore slower and increase the chances for a hard stop at the track's end.
In light of the above, there is need for improved methods for transporting and quenching hot coke which allow for short cycle times between oven pushes, the separation of hot caked coke into loose bulk coke prior to quenching, and also cost effective collection of dust generated during the separation process. There is also need for improved methods for transporting and quenching hot coke which utilize a minimum number of mobile machines which are configured such that the machines may not interfere with one another during normal operation.